Concentrated sulfuric acid-dye solution dyeing

ABSTRACT

Various types of fibers, especially fibers which can ordinarily only be dyed with some difficulty, are dyed in a relatively short period of time at a relatively low temperature by using a dye bath in which the dye is dissolved in concentrated sulfuric acid, and in which a buffering compound, such as an alkali salt of a weak acid, is preferably added.

United States Patent Miyasaka 14 1 Mar. 28, 1972 [54] CONCENTRATEDSULFURIC ACID-DYE 2,400,720 5/1946 Stauding'er ..8/168.2 SOLUTION DYEING3,129,053 4/1964 Castle ..s/93 3,154,613 10/1964 Epstein 260/308Inventor Kaluo Miyasaka, Toklwadia, 3,346,322 10/1967 'Finkenauer ..s/79Itabashi-ku, Tokyo, Japan 3,391,985 7/1968 Zarbachen.... ..8/54 [22]Filed Sept 23 1969 2,684,812 12/1958 Bossard ..8/l77 AB l [21] APP] NOJ860,436 OTHER PUBLICATIONS Hindle, Papers of the American Associationfor Textile [52] U S Cl I 854 Technology, March 1957, pages 18-20 8/38,8/41 R, 8/41 A, 8/41 B, 8/41 C, 8/41 D, 8/39, Primary Examiner DonaldLevy 8/92, 8/82, 8/162 B, 8/ 162 R, 8/168, 8/175, 8/177 Ammey 0blnFisher & Spivak R, 8/177 AB, 8/178 R, 8/178 E, 117/138.8 D, 117/l38.8 E,117/138.8 F,117/138.8 N, 117/138.8 [57.] ABSTRACT R, 117/141, 264/143,264/78 [51] Int. Cl. ..D06p 3/14 Various yp of fibers, p i l y fi erwhich can ordinarily 53 Field of Search ..8/82, 79; zen/30.8; 264/78 ybe y with some difficulty, are y in a relatively short 4 period of timeat a relatively low temperature by using a dye [56] References Citedbath in which the dye is dissolved in concentrated sulfuric acid, and inwhich a buffering compound, such as an alkali salt of a weak acid, ispreferably added.

5 Claims, No Drawings CONCENTRATED SULFURIC ACID-DYE SOLUTION DYEINGBACKGROUND OF THE INVENTION 1. Field of Invention This invention relatesto a process for dyeing natural and synthetic fibers and syntheticpolymers at a relatively low temperature and at a relatively acceleratedspeed.

2. Description of Prior Art It is well known that retarding agents canbe used in a fiber dyeing solution in order to maintain a more uniformlycolored fiber. It is also well known that the dye bath can be heated toaccelerate the fiber dyeing process and thereby produce a more deeplycolored product. In order to dye a difficultly dyeable synthetic fiber,a superheating process or a thermosol dyeing process should be employed.The difficulty of this type of process, however, is that the heated dyebath frequently causes fiber damage.

In conventional dyeing processes, a fiber is dyed in a hot dye bath foran extended period of time. Accordingly, it is necessary to use a batchtype process in dyeing various fibers, and especially in dyeing thedifficultly dyeable synthetic fibers. Although using a batch process hasthe disadvantage that it is difficult to make the color of fiberuniform, nevertheless, since the dyeing process requires a period of atleast 30 minutes to one hour, a continuous system is impractical. Inorder to dye a difficultly dyeable synthetic fiber, the dye should bediffused into the microstructure of fiber and be fixed to it.

Although various types of accelerators and other agents have beenstudied in order to obtain a more uniformly and deeply colored product,heretofore, no completely satisfactory technique has been developed.

SUMMARY OF THE INVENTION It is an object of this invention to provide aquick dyeing process at a relatively low temperature and at a relativelyhigh speed.

It is another object of this invention to provide a continuous processfor dyeing fibers at a relatively low temperature and at a relativelyhigh speed to provide a deep, clear color having excellent fastness tolight and to washing.

Other objects of this invention will become apparent as the descriptionof the invention proceeds. These and other objects have now herein beenattained by the following process:

A dye which is soluble and non-reactive with sulfuric acid is dissolvedin concentrated sulfuric acid. A buffering compound, such as an alkalisalt of a weak organic or inorganic acid, is added to the sulfuric acidsolution to make a dye bath. An acid-resistant fiber, especially adifficultly dyeable synthetic fiber, is passed through the dye bath at arelatively low temperature and at a relatively high speed, whereby thedye is diffused into the internal microstructure of the fiber. The fiberis then treated with water or an alkali solution in water or an alkalisolution bath, so that the dye which has been fused into the fibersinternal microstructure is crystallized out and fixed to the internalmicrostructure. The fiber is then washed and dried, if necessary,steamed, to obtain a clear, deep color, having excellent fastness toboth light and wash- DETAILED DESCRIPTION OF THE INVENTION The typicalquick dyeing process of this invention consists of the following foursteps:

FIRST STEP A dye which is soluble and resistant to sulfuric acid ismixed with concentrated sulfuric acid and is dissolved by heating. Aftercooling, a buffering compound such as an alkali salt of a weak acid isadded to the solution with intense stirring. Surface active agents,retarding agents, or accelerating agents, can also be added to the dyebath, if desired.

SECOND STEP An acid-resistant fiber, and especially a difficultlydyeable synthetic fiber or a plastic material, is passed through the dyebath in 50 to 60 Centigrade, at a relatively high speed. The dyesolution is then uniformly squeezed out, so that up to about 50 percentof the dye solution remains. At this point, the dye is diffused into theinternal microstructure of the fiber.

THIRD STEP The treated fiber is then contacted with water or an alkalisolution, so as to cause an acid-base reaction which generates thermalenergy. The dye dissolved in sulfuric acid is precipitated by thereaction and is fixed into the internal microstructure of the fiber bythermal energy. All of the remaining dye in the fiber, which isphysically absorbed, is then washed out with water.

FOURTH STEP The washed fiber is dried and heat-treated to fix the dye.

Examples of dyes and pigments which may be used for the dye bath of thisinvention are as follows:

1 Aromatic Condensation Polycyclic Dyes 1.

This type of dye is usually dissolved in more than 90 percentconcentrated sulfuric acid, preferably 95 percent concentrated sulfuricacid, at 7075 C. Ponsol orange RRT(C.I.59,705), Mikethrene Marine Blue G(C.I.7l,200), Indanthrene Dark Blue BT(C.I.59,800), NihonthreneBrilliant Green GREEN B(C.I.59,825), Heliudone Black .IBB(C.I.62,230),Authra Green B(C.I.69,500), Cibanone Violet R Extra(C.I.60,0l0), CaldeonBrilliant Purple RR Extra(C.l.63,365), Vat Red Brown 2R(C.I.69,0l5) andAlgol Scarlet R(C.I.73,030).

2. Anthraquinone Vat Dyes This type of dye is usually dissolved in 90percent and preferably 95 percent concentrated sulfuric acid at 6065 C.Indanthrene Brown G(C.I.69,015), Caledon Yellow G(C.I.65,425),Flavanthrene R(C.I.70,600), Ponsol Red Violet RRNR(C.I.67,895), VatGreen BB(C.I.58,825), Anthra Red RT(C.I.65,215), Cibanone YellowGC(C.I.67,300), Algol Brilliant Violet 2B(C.I.60,0l I), Durindone Blue GCD(C.I.78,065), Helindone Yellow .IB(C.I.70,605).

3. Indigoide Vat Dyes This type of dye is usually dissolved in more thanpercent, and preferably more than percent concentrated sulfuric acid at55-60 C. Brilliant Indigo BASF(C.I.73,035), Mitsui Brilliant Tsuy IndigoB(C.I.73,040), Ciba Violet 4B(C.I.6l,1003B(C.l.73,360), Algol VioletBBN(C.I.73,370), Thioindigo Scarlet T(C.I.73,635), Helindone Blue3GN(C.I.73,825), Anthra Scarlet GG(C.I.73,355), Durindone Red3B(C.l.73,385), Hydron Blue 3b(C.I.53,630).

4. Basic Dyes This type of dye is usually dissolved in more than 40percent, and preferably more than 60 percent, concentrated sulfuric acidat 6570 C. Methyl Green Crystal(C.I.42,590), Acridine Red3B(C.I.45,000), Rhoduline Orange N(C.I.50,2l5), NeutralBlue(C.I.50,l50), Methyl Violet R(C.I.42,535), Victoria pure BlueBO(C.I.44,045), Safranine T Extra(C.I.50,240), ThioflavineS(C.I.49,005), Janus Brown R Induline Scarlet (C.I.33,500).

5. Anthraquinone Acidic Dyes and Other Acidic Dyes.

This type of dye is dissolved in more than 40 percent of sulfuric acid.Brilliant Acid Green 6B(C.I.42,l00), Xylene Milling Blue BL(C.I.50,315),Fast Acid-Violet B(C.I.42,571), Rosinduline 2G(C.I.50,l20), Acid Violet4R(C.I.22,895), Acilan Saphirol SE(C.I.50,120), Alizarine Sky BlueB(C.I.62,105), Supracene Red BBT(C.I.68,200), Sapramine GreenFB(C.I.62,5 l5), Carbolan Blue B(C.I.62,075), Anthra Red B(C.I.23,9l0),Supramine Blue R(C.I.l7,055), Fast Light Yellow G(C.I.l8,820),Naphthylamine Black 4B(C.l.20,47016,0l 1), Victoria Fast Violet(C.I. 13,455), Amido NaphtholRed 6B(C.I.18,055 Naphthol Dark GreenG(C.l.20,495), Light Fast Yellow 3G(C.l.18,96015,7ll).

6. Sulfide Dyes This type of dye is usually dissolved in more than 85percent, and preferably more than 90 percent, of concentrated sulfuricacid at 6065 C. Pyrogen Brilliant Violet R(C.l.53,700), SulphurBrilliant Green GG(C.I.53,570), Sulfogene Carbon MCF(C.I.53,195),lmmedial Coriath B Extra(C.l.53,260), Hydron Blue G(C.I.53,640), KatigenIndigo R Extra(C.l.53,440), Thionol Orange RR(C.I.53,050), Eclipse RedViolet(C.I.53,228), Thiogen Black(C.l.53,290), Chionone Sky Blue6B(C.l.53,450).

7. Organic Pigment This type of pigment is usually dissolved in morethan 90 percent and preferably 95 percent, concentrated sulfuric acid at70-75 C. Heliogen Green B(C.l.74,280), Monostral Fast BlueGS(C.I.74,100), Hansa Yellow R(C.I.12,7l), Vulcan Fast RedB(C.l.2l,l20), Pigment Fast Yellow G(C.I.18,700), Permanent Orange GExtra(C.l.l2,060), Vulcanosine Fast Blue GG(C.I.69,800),Phthalogen-Brilliant Green lFFB(C.l.74,280), Helio Fast PinkRL(C.I.60,745), lrgalite Orange PG(C.I.21,110).

8. Direct Dyes This type of dye is usually dissolved in more than 60percent of sulfuric acid at 6080 C. Pontamine Fast YellowWBF(C.l.l9,555), Alizarine Direct Violet EEF(C.I.62,005), l-lelio FastBlue Bl .(C.l.63,005), Benzopurpurine 10B(C.l.23,50022,570), PyramineOrange R(C.l.24,900), Catechu Brown B(C.I.35,520), Columbia BlackFB(C.I.35,730), Diazo Brilliant Green 3G(C.l.28,2802B(C.l.14,785).

9. Dispersed Dyes This type of dye is usually dissolved in more than 40percent of sulfuric acid at 6080 C. Celliton Fast Red Violet RN(C.l.11,120), Cibacet Red 3B(C.l.60,7l0), Celanthrene Fast Pink 3B(C.l.62,015Serisol Fast Red 3BL(C.I.61,140), Duranol Brilliant Blue CB(C.I.64,500),Dispersol Fast Orange B(C.I.26,080), Setacyl Scarlet B(C.l.l1,ll0),Artisil Direct Brown H(C.l.l 1,100), SRA Rubine B(C.l.ll,070), SupracetFast Violet B(C.l.6l,105).

As mentioned above, the dyes are usually dissolved in more than 60percent concentrated sulfuric acid and preferably more than 80 percentconcentrated sulfuric acid. Some types of dyes are insoluble in dilutesulfuric acid or even in concentrated sulfuric acid. In that case, themixture of dye and sulfuric acid should be heated in order to form thesolution. Certain types of dye such as anthraquinoloids can be dissolvedin more than 90 percent of sulfuric acid by heating.

Suitable buffer compounds which are useful in the present inventioninclude the alkali salts of organic or inorganic acids, such as sodiumcarbonate, sodium bicarbonate, sodium borate, sodium acetate, sodiumtartarate, sodium lactate and the like. When the solubility of the dyein the dye bath is sufficient, the buffering compound added to the dyebath depends upon the solubility of the dye and the type of fiber orpolymer. Where wool, polyamide fiber or other material which is lessresistant toward sulfuric acid is dyed, the amount of the buffercompound is increased in order to prevent damage.

Certain buffer compounds, such as sodium citrate or sodium tartarate areespecially desirable in that they tend to improve the solubility of thedye in the dye bath. Usually, the solubility of the dye in concentratedsulfuric acid is decreased by adding inorganic alkali compounds, such assodium carbonate; however, addition of sodium citrate or sodiumtartarate or certain other organic compounds, may actually increase thesolubility of the dye in the dye bath. The buffering compound generallyacts to improve the accessibility of the dye into the internal structureof the polymer or fiber and thereby enhance the diffusion of the dyeinto the internal structure. Even when nonaqueous dye baths are used,the buffer was observed to enhance diffusion. Usually, an inorganic typeof buffer compound is used together with an organic type of buffercompound. The total amount of buffer compound should be insufficient,however, to tie up all of the sulfuric acid, since sufficient acidshould be present to prevent premature precipitation of the dye untilthe fiber is treated with the neutralization bath.

Other additives may also be added to the dye bath, such as aluminumsulfate, copper sulfate, chromium sulfate, aniline, or naphthylamine.Also, nonionic surface active agents may be added, if necessary, such asalkylbenzene sulfate, liquid glue or glycerine. Other conventionaladditives may also be added, if necessary.

The dyeing process of this invention can be used for color- I ing a widevariety of fibers, films, shaped articles, powders or granules such aspolypropylene, polyethylene polyether, polyester, polyacrylics,polyvinylchloride, polyvinylidine chloride, polyurethane, and polyamidefibers, as well as animal fibers, such as wool.

The difficultly dyeable synthetic fibers, such as polypropylene,polyethylene, polyether, polyester, polyacrylics, polyvinylchloride, orpolyvinylidine chloride, have no affinity for dyes having sulfonicradicals or other strong hydrophilic radicals, accordingly,water-insoluble dyes should be used. Polyamide fibers are less resistanttoward concentrated sulfuric acid and accordingly, a buffer compoundsuch as sodium carbonate, sodium bicarbonate, sodium borate, and alkalisalts of organic acids should be added to the dye bath in order toprevent damage. Part of the sulfuric acid is reacted with a buffercompound to produce sodium bisulfate, or sodium sulfate, and weak acids,such as carbonic acid, boric acid, and acetic acid. These componentsimpart a buffering action to prevent fiber damage. Moreover, the weakacid acts to loosen the internal structure of the fiber in order toallow more ready diffusion of the dye into the fiber structure. Wool andother fibers having less resistance toward sulfuric acid, should betreated with a dye bath having'a suitable amount of a buffer compound.

The many advantages of the accelerated dyeing process of this inventioncan be enumerated as follows:

1. The efficiency of the dyeing process is quite improved, since thedesired deep color is obtained by dyeing at rather low temperatures fora relatively short period of time.

2. difiicultly dyeable synthetic fibers which have heretofore only beendyed by thermosol methods, or by high temperature treatments, can beeasily dyed by this process.

3. High crystalline synthetic fibers can be dyed by this process toproduce deep color effects.

4. Heretofore, only specific dyes were usable for dyeing a difficultlydyeable synthetic fiber. By the present process, however, various typesof commercial dyes can be used.

5. Since dyeing time is quite short and dyeing temperature is quite low,the present process does not damage the fibers as frequently occurs byconventional dyeing methods.

The characteristic operations and results of the process of thisinvention are as follows:

1. Water-insoluble dyes, such as vat dyes, sulfide dyes, or ganicpigments and water-dispersing dyes can be used by dissolving the dye inconcentrated sulfuric acid to form the dye bath. It is indispensable todissolve the dye so that it can be diffused into the microstructure ofthe fiber. The water-insoluble dyes which has first been completelydissolved can be maintained in stable condition despite changes intemperature or the addition of additives. The presence of sulfuric acidtherefore acts to accelerate the diffusion of the dye molecule byswelling the fiber. Sulfuric acid also acts to accelerate the absorptionof the dye or pigment and it accelerates the fixing of the dye in thefiber. This latter effect is obtained by the thermal energy formed bythe reaction of sulfuric acid with water or alkali solution.

2. Quick dyeing at low temperatures is achieved by using a concentrateddye bath. ln order to quickly diffuse a dye into a fiber, a concentrateddye which is dissolved in the form of a molecule is preferably employed.If the dye bath is formed from a concentrated sulfuric acid, thedyeability of thedye is increased to a very high level. Moreover, if theconcentration of the dissolved dye is high, the level of dyeability iseven further increased. Accordingly, dyeing at low temperatures becomespossible.

3. Most of the water-soluble dyes are quickly dissolved in concentratedsulfuric acid and the diffusion of dye depends on the concentration ofdye in the dye bath.

4. In order to prevent damage caused by concentrated sulfuric acid, andin order to prevent surface dyeing, a strong alkali salt of organic orinorganic weak acid is added to the dye bath. It is generally desirableto use a buffering agent, although use of such agent is not mandatory.Depending upon the particular dye and the particular type of fiber beingtreated, a buffering agent should be added to prevent rapid dyeing ofthe fiber surface or swelling and dissolution of the fiber by thesulfuric acid. When the fiber is dyed on its surface rather than in itsinternal microstructure, its color brightness can be easily reduced. Thebuffer compound is also desirable in that it accelerates the fusion ofthe dye into the internal microstructure of the fiber to give a brightcolor and actual fixing. Where the dye is not fixed to the mainstructure, its presence can cause fiber melting, shrinking, hardening oryellowing when the fiber is subsequently washed in water or an alkalisolution whereby heat is generated by the acid-base reaction.

5. A quick dyeing within as short a period of time as one to one hundredand twenty seconds is possible by the process of this invention.

Conventional dyeing methods have required about one or two hours fordyeing. On the other hand, there are difficultly dyeable fibers whichare dyeable only at high temperatures, or by thermosol dyeing. However,by the present process, such difficultly dyeable fibers can be dyed atlow temperatures within short periods of time. Moreover, excellent lightand wash fastness is rendered by the process of this invention.

Some fibers can be damaged by high temperatures, or by extended dyeingperiods, but by the present process, these difficulties can be avoided.Quick dyeing is now possible for the previously difficultly dyeablefibers and is unnecessary to decrease the crystallinity of the fiber inorder to render it dyeable as in the prior art. The present process,therefore, is quicker and less costly in terms of labor, heat energy andelectrical energy and other costs involved in dyeing a fiber.Furthermore, by the present process, it is now possible to operatecontinuously rather than batch-wise as in the prior art.

EXAMPLE 1 Process For Dyeing Polypropylene And PolyvinylidenechlorideFiber First Step: 6 parts of phthalocyanine Blue is mixed with 200 partsof 98 percent of sulfuric acid and is completely dissolved by heating at65 C. After cooling to 50 C., 50 parts of sodium acetate, and 1 part ofglycerine are added and dissolved under intense agitation to form thedye bath.

Second Step: 20 parts of polypropylene fiber fabric is passed throughthe dye bath prepared by the First Step for 2 minutes under stirring,and then is uniformly squeezed.

Third Step: The polypropylene fiber fabric treated by the Second Step isimmersed in cool water, whereby the dye finely dispersed and fixed inthe fir. The fabric is washed with water and then is passed through 40times by weight of 2 percent sodium carbonate solution in order toneutralize the sulfuric acid remaining on the fabric. The fabric is thenwashed and dehydrated.

Fourth Step: The polypropylene fabric treated by the Third Step is driedin a ventilation drier at 60 C., and then is steamheated at 115 C. for20 minutes, to complete the fixing and coloring. The clear and deepcolor polypropylene fabric having excellent fastness to light andwashing is obtained by said steps. Polyvinylidene chloride fiber fabricis treated by the same process stated in the First, Second Third andFourth Steps. The same results are obtained when other water-insolublevat dyes, sulfide dyes or organic pigments are used instead ofphthalocyanine Blue.

EXAMPLE 2 Process For Dyeing Polyether, Polyvinylchloride AndPolyethylene Fiber First Step: 10 parts of Mikethlene Yellow GCN ismixed with 200 parts of 98 percent concentrated sulfuric acid and iscompletely dissolved by heating at 50 C. 50 parts of sodium acetate, 1part of sodium alkyl benzene sulfonate and 2 parts of aluminum sulfateare added and dissolved under severe agitation.

Second Step: parts of polyether fiber fabric is passed through the dyebath prepared by the First Step for seconds under stirring, and then isuniformly squeezed.

Third and Fourth Steps: The same steps stated in Example 1 are employed.

The clear and deep color polyether fabric having excellent fastness tolight and washing is obtained by said steps. Each of polyvinyl chloridefiber fabric and polyethylene fiber fabric is treated by the sameprocess stated in the First, Second, Third and Fourth Steps, excepteliminating the steaming step. The same results are obtained in eachcase. Other water-insoluble vat dyes, sulfide dyes or organic pigmentsmay be used instead of Mikethlene Yellow GCN with good results.

EXAMPLE 3 Process For Dyeing Polyester And Polyurethane Fiber FirstStep: 8 parts of Sulphur Brilliant Green 06 is mixed with 200 parts of90 percent concentrated sulfuric acid and is completely dissolved byheating at 65 C. After cooling to 55 C., 60 parts of sodium acetate, 10parts of sodium carbonate, and 1 part of a nonionic surface active agentis added and dissolved under intense agitation.

Second Step: 30 parts of polyester fiber fabric is passed through thedye bath prepared. by the First Step for 1 minute under stirring, andthen is uniformly squeezed.

Third and Fourth Steps: The same steps stated in Example 1 are employed.

A clear color polyester fabric having excellent fastness to light andwashing, is obtained by said steps. Polyurethane fiber fabric is treatedby the same process stated in the First, Second, Third and Fourth Steps.A clear and deep color polyurethane fabric having excellent fastness tolight and washing is obtained. Other water-insoluble vat dyes, sulfidedyes or organic pigments may be used instead of Sulphur Brilliant GreenGG, with similar results.

EXAMPLE 4 Process For Dyeing Polyacrylic Fiber First Step: 10 parts ofIndanthrene Brilliant Orange RK is mixed with 200 parts of percentconcentrated sulfuric acid and is completely dissolved by heating at 60C. 50 parts of sodium acetate, 20 parts of sodium carbonate and 1 partof nonionic surface active agent is added and dissolved under intensestirring, to make the dye bath.

Second Step: 20 parts of polyacrylic fiber fabric is passed through thedye bath for 30 seconds at 60 C. under stirring, and then is uniformlysqueezed.

Third and Fourth Steps: The same steps stated in Example 1 are employed.

A clear color polyacrylic fabric having excellent fastness to light andwashing is obtained by said steps. Other water-insoluble vat dyes,sulfide dyes or organic pigments may be used instead of the lndanthreneBrilliant Orange RK.

EXAMPLE 5 Process For Dyeing Polyester Fiber First Step: 4 parts ofResoline Red PE is mixed with 200 parts of 60 percent concentratedsulfuric acid and is dissolved by heating. After cooling to 40 C., 50parts of sodium tartarate, 100 pans of sodium acetate, 30 parts ofsodium bicarbonate, 120 parts of sodium carbonate, parts of sodiumsulfate and parts of aniline are added and dissolved under severeagitation to make the dye bath.

Second Step: 25 parts of polyester fiber fabric is passed through thedye bath prepared by the First Step, for 1 minute, under stirring, at 75C., and then is uniformly squeezed.

Third and Fourth Steps: The same steps stated in Example are employed.The clear and deep color polyester fabric having excellent fastness tolight and washing is obtained by said steps. Each of polyvinylidenechloride fiber, polypropylene fiber, polyester fiber, polyurethane fibercan be dyed with the same process. When dyeing polyvinyl chloride fiberor polyethylene fiber, the treatment in the dye bath should be for 30seconds instead of 1 minute, and the steaming in the Fourth Step shouldbe omitted. Other dispersion dyes or anthraquinone milling dyes may beused instead of Resoline Red FB, with similar results.

EXAMPLE 6 Process For Dyeing Various Synthetic Fibers First Step: 3parts of Methyl Violet Extra is mixed with 200 parts of 80 percentconcentrated sulfuric acid, and is completely dissolved by heating to 80C. 50 partsof sodium acetate, 20 parts of sodium carbonate and 1 part ofsodium alkylbenzene sulfonate are gradually added to it under intenseagitation to make the dye bath.

Second Step: Where polyvinyl chloride fiber, polyethylene fiber,polyether fiber or polyacrylic fiber is dyed, the dye bath is cooled to50 C. Where either polyurethane fiber or polyester fiber is dyed, thedye bath is cooled to 65 C. Where polypropylene fiber is dyed, the dyebath is kept at 80 C. 20 parts of each fiber fabric is passed throughthe dye bath prepared by the First Step for 1 minute under stirring, andis uniformly squeezed. Third and Fourth Steps: The same steps stated inExample 1 are employed, except when dyeing polyvinyl chloride, orpolyethylene fiber, steaming in the Fourth Step is omitted. A clear anddeep colored fabric having excellent fastness is obtained in each case.Other basic dyes may be used instead of Methyl Violet Extra with similarresults.

EXAMPLE 7 Process For Dyeing Various Synthetic Fibers First Step: 8parts of Direct Brilliant Blue RW is mixed with 200 parts of 80 percentconcentrated sulfuric acid, and is completely dissolved by heating at 80C. parts of sodium acetate and 1 part of nonionic surface active agentis mixed and dissolved under intense agitation to make the dye bath.Second Step: Where polyvinyl chloride fiber, polyurethane fiber,polyether fiber or polyacrylic fiber is dyed, the dye bath is cooled to80 C. 20 parts of each fiber fabric is passed through the dye bathprepared by the First Step for 1 minute under stirring, and is uniformlysqueezed.

Third Step: EAch fiber fabric treated by the Second Step is immersed inthe solution consisting of 2 parts of aluminum sulfate and 100 parts ofwater at 60 C. for 2 minutes, and then is washed with water anddehydrated by squeezing.

Fourth Step: When dyeing polyvinyl chloride fiber or polyethylene fiber,the treated fabric is dried in a ventilation drier. When dyeing otherfibers, the treated fabric is dried in a ventilation drier and thensteam-heated at 115 C. for 20 minutes. A clear and deep colored fabrichaving excellent fast ness to light and washing is obtained by saidsteps in each case. Other direct dyes may be used instead of DirectBrilliant Blue RW with similar results.

EXAMPLE 8 Process For Dyeing Polyamide Fiber With Direct Dye First Step:10 parts of Direct Orange R is mixed with and uniformly dispersed in 200parts of concentrated sulfuric acid,

and then the dye is completely dissolved by gradually heating to C. Thedye solution is cooled to 60 C. by standing at room temperature, afterdissolving. Under severe agitation, 50 parts of sodium acetate, and 120parts of sodium carbonate are added to the dye solution, and then 0.5parts of sodium alkyl benzene sulfonate is mixed with it to make the dyebath. Second Step: At 60 C., 40 parts of polyamide fiber fabric ispassed through the dye bath prepared by the First Step, for 30-60seconds, whereby the dye is uniformly adsorbed in the fiber, and the wetpolyamide fiber fabric is uniformly squeezed so that up to 50 percent,and preferably up to 35 percent of the dye solution remains. Third Step:The polyamide fiber fabric treated by the process of the Second Step, ispassed through a water bath to wash it, and to remove the dye which isphysically adsorbed on the fiber, sulfuric acid and other components ofdye bath. The dye adsorbed in the 'fiber is thereby stably fixed in thefiber. The treated fabric is passed through 40 times by weight of alkalisolution made of parts of water and 1 part of 28 percent of ammoniasolution for two minutes to neutralize the sulfuric acid remaining onthe fabric. Then, it is washed and dehydrated. Fourth Step: Thepolyamide fiber fabric treated by the process of the Third Step is driedin a ventilation drier at 60 C., and then is steam-heated at C., for 20minutes, to completely fix the dye on the fiber and to complete thecoloring. The clear orange color polyamide fiber fabric is obtained bythe process. Other direct dyes may be used instead of Direct Orange Rwith similar results.

EXAMPLE 9 First Step: 5 parts of Rhodamine 5G is mixed with anduniformly dispersed in 200 parts of concentrated sulfuric acid, and thenthe dye is completely dissolved by gradually heating to 75 C. The dyesolution is cooled to 60 C. by standing at room temperature afterdissolving. Under intense agitation, 30 partsof sodium acetate, 20 partsof sodium lactate, 75 parts of sodium carbonate, 25 parts of sodiumbicarbonate, and 1 part of a nonionic surface active agent, are added tothe dye solution, and then 100 parts of water is added to make the dyebath.

Second Step: At 45 C., 40 parts of polyamide fiber fabric is passedthrough the dye bath prepared by the First Step, for

20-30 seconds, whereby the dye is uniformly adsorbed into the fiber. Thewet fabric is then uniformly squeezed so that up to 50 percent, andpreferably up to 35 percent of the dye solution remains to prevent colorspot.

Third Step: The polyamide fiber fabric treated by the process of theSecond Step, is washed with cold water to remove the dye which isphysically adsorbed on the fiber, sulfuric acid and other components ofthe dye bath, so that the dye adsorbed into the fiber is stably fixed inthe fiber. The treated fabric is passed through 40 times by weight ofalkali solution made of 100 parts of water and 0.3 part of sodiumcarbonate, for 2 minutes to neutralize the sulfuric acid remaining onthe fabric. Then it is washed and dehydrated.

Fourth Step: The same step stated in Example 8 is employed. The clearand deep red color polyamide fiber fabric is obtained by the process.Other basic dyes may be used instead of Rhodamine 5G with similarresults.

EXAMPLE 10 Process For Dyeing Polyamide Fiber With Acidic Dye FirstStep: 5 parts of Fast Red B is mixed with and uniformly dispersed in 200parts of 80 percent concentrated sulfuric acid, and then the dye iscompletely dissolved by gradually heating to 70 C. The dye solution iscooled to 60 C. by standing at room temperature, after dissolving. Underintense agitation, parts of sodium acetate, 200 parts of sodiumcarbonate, l part of a nonionic surface active agent, are added to formthe dye bath.

Second Step: At 50 C., 30 parts of polyamide fiber fabric is passedthrough the dye bath prepared by the First Step,-for -30 seconds,whereby the dye is uniformly adsorbed into the fiber and then the wetfabric is uniformly squeezed so that up to 50 percent, and preferably upto 35 percent of the'dye solution remains to prevent color spotting.

Third and Fourth Steps: The same steps stated in Example 8 are employed.A bright and deep color polyamide fiber fabric is obtained by theprocess. Other acidic dyes may be used instead of the Fast Red B withsimilar results.

EXAMPLE 1 1 Process For Dyeing Polyamide Fiber With Dispersion Dye FirstStep: 3 parts of Resoline Blue FBL is mixed with 200 parts of 60%concentrated sulfuric acid and is dissolved by heating. After cooling to60 C., 120 parts of sodium acetate, 30 parts of sodium tartarate, and150 parts of sodium carbonate are added and dissolved under intenseagitation to make the dye bath.

Second Step: 40 parts of polyamide fiber fabric is passed through thedye bath prepared by the First Step for 30 seconds, under constantstirring at 60 C., and then is uniformly squeezed as described inExample 10.

Third and Fourth Steps: The same steps stated in Example 8 are employed.

A bright and deep shade color polyamide fabric having excellent fastnessto light and washing is obtained by said steps. Other dispersion dyesmay be used instead of Resoline Blue FBL with similar results.

EXAMPLE 12 Process For Dyeing Animal Fiber With Vat Dye First Step: 7parts of Ponsol Golden Orange 36 is mixed with and uniformly dispersedin 200 parts of 96 percent concentrated sulfuric acid, and then the dyeis completely dissolved by gradually heating to 70 C. The dye solutionis cooled to 50 C. by standing at room temperature. Under intenseagitation, 50 parts of sodium acetate, parts of sodium carbonate and 0.5part of nonionic surface active agent are added to it to make the dyebath.

Second Step: 30 parts of wool fabric is passed through the dye bathprepared by the First Step, for 30 seconds, at 60 C., whereby the dye isuniformly adsorbed into the fiber, and is uniformly squeezed so that upto 50 percent of the dye solution remains to prevent color spotting.

Third Step: The wool fabric treated by the process of the Second Step,is washed with cold water to remove the dye which is physically adsorbedon the fiber, sulfuric acid and other components of dye bath, wherebythe dye adsorbed into the fiber is solidified and stably fixed in thefiber. The treated fabric is passed through 40 times by weight of alkalisolution made of 100 parts of water and 1 part of 28 percent of ammoniasolution for 2 minutes at room temperature to neutralize the remainingsulfuric acid and is then washed and dehydrated.

Fourth Step: The wool fabric treated by the process of the Third Step isdried in a ventilation drier, and then is steamheated at 1 15 C. for 20minutes to fix the dye on the fiber and to complete the coloring. Aclear and deep blue colored wool fabric is obtained by the process.Other vat dyes may be used instead of Ponsol Orange 30 with similarresults.

EXAMPLE 13 Process For Dyeing Wool With Sulfide Dye First Step: 6 partsof Carbanol Blue LB is mixed with and uniformly dispersed in 200 partsof 90 percent concentrated sulfuric acid, and then the dye is completelydissolved by gradually heating to 60 C. The dye solution is cooled to 50C. by standing at room temperature. Under intense agitation, 30 parts ofsodium acetate, 20 parts of sodium lactate, and 20 parts of sodiumborate are gradually added and 1 part of liquid acetyl-glue is added toform the dye bath.

Second Step: 30 parts of wool fabric is passed through the dye bathprepared by the First Step, for 30-60 minutes, 70 C., and is uniformlysqueezed so that up to 50 percent of the dye solution remains to preventcolor spotting.

Third and Fourth Steps: The same steps stated in Example 10 areemployed. A clear and deep green colored wool fabric is obtained by theprocess. Other sulfide dyes may be used instead of the Carbanol Blue LBwith similar results.

EXAMPLE 14 Process For Dyeing Wool With Acidic Dye First Step: 6 partsof Brilliant Orange RN is mixed with and uniformly dispersed in 200parts of percent concentrated sulfuric acid, and then the dye iscompletely dissolved by gradually heating to 65 C. Under intenseagitation, 50 parts of sodium acetate, 30 parts of sodium tartarate and0.5 part of nonionic surface active agent are gradually added, anddissolved, to form the dye bath.

Second Step: 35 parts of a wool fabric is passed through the dye bathprepared by the First Step for 30 minutes, at 60 C., and is uniformlymangled so that up to 50 percent of the dye solution remains to preventcolor spotting.

Third and Fourth Steps: The same steps stated in Example 10 areemployed.

A deep, clear orange colored wool fabric is obtained by the process.Other acidic dyes may be used instead of Brilliant Orange RN withsimilar results.

EXAMPLE 15 Process For Dyeing Wool With Basic Dye First Step: 3 parts ofcrystal Violet 6B is mixed with and uniformly dispersed in 200 parts of80 percent concentrated sulfuric Tacid, and then the dye is completelydissolved by gradually heatingto 70 C. After cooling to 50 C. at roomtemperature, 50 parts of sodium acetate, 20 parts of sodium lactate, 10parts of sodium bicarbonate and 0.5 parts of nonionic surface activeagent are gradually added and dissolved under intense agitation, to makethe dye bath.

Second Step: 35 parts of wool fabric is passed through the dye bathprepared by the First Step, for30 minutes, at 60 C., and uniformlysqueeced so that up to 50 percent of the dye solution remains to preventcolor spotting Third and Fourth Steps: The same steps stated in Example10 are employed.

A clear and deep orange colored wool fabric is obtained by the process.Other basic dyes may be used instead of Crystal Violet 6B, with similarresults.

EXAMPLE 16 Process For Dyeing Wool With Direct Dye First Step: 6 partsof Oxamine Red is mixed with and uniformly dispersed in 200 parts of 80percent concentrated sulfuric acid, and then the dye is completelydissolved by gradually heating to 70 C. After cooling to 50 C. at roomtemperature, 50 parts of sodium acetate and 20 parts of sodium carbonateare added and moreover 0.5 part of sodium alkyl benzene sulfonate isadded and dissolved under severe agitation to make the dye bath. SecondStep: 30 parts of wool fabric is passed through the dye bath prepared bythe First Step for 30 minutes, at 60 C., and uniformly squeezed so thatup to 50 percent of the dye solution remains to prevent color spotting.Third and Fourth Steps: The same steps stated in Example 10 areemployed. A clear and deep red colored wool fabric is obtained by theprocess. Other direct dyes may be used instead of Oxamine Red, withsimilar results.

What is claimed is:

l. A process for quick dyeing which comprises:

preparing a dye bath for dissolving into sulfuric acid 60 a dye which issoluble and non-reactive with said acid, passing a fiber or film,through said dye bath whereby the dye is diffused into the internalstructure of said fiber or film, contacting said treated substance withwater or an alkali solution whereby the dye is solidified and fixed intothe internal structure of said fiber or film, and, washing and dryingsaid fiber or film.

2. The process of claim 1, wherein an alkali salt of a weak inorganic ororganic acid of more than 40 percent concentration by weight of solutionbuffering compound is added to the dye bath.

3. The process of claim 1, wherein the dye bath is maintained at atemperature of up to about 70 C.

4. The process of claim 1, wherein sodium citrate or sodium tartarate isadded to said dye bath containing the sulfuric acid and the inorganicbuffering compound.

5. A process for quick dyeing which comprises preparing a dye bath bydissolving into sulfuric acid of more than 60 percent concentration, adye which is soluble and non-reactive with said acid, 26

passing a fiber or film through said dye bath whereby the film isdiffused into the internal structure of said substance, wherein said dyebath is maintained at a temperature of up to about C., contacting saidtreated fiber or film with water or an alkali solution so as to generatesufficient thermal energy to fix the dye into the internal structure ofthe fiber or film, washing and drying said fiber or film.

2. The process of claim 1, wherein an alkali salt of a weak inorganic ororganic acid of more than 40 percent concentration by weight of solutionbuffering compound is added to the dye bath.
 3. The process of claim 1,wherein the dye bath is maintained at a temperature of up to about 70*C.
 4. The process of claim 1, wherein sodium citrate or sodium tartarateis added to said dye bath containing the sulfuric acid and the inorganicbuffering compound.
 5. A process for quick dyeing which comprisespreparing a dye bath by dissolving into sulfuric acid of more than 60percent concentration, a dye which is soluble and non-reactive with saidacid, 26 passing a fiber or film through said dye bath whereby the filmis diffused into the internal structure of said substance, wherein saiddye bath is maintained at a temperature of up to about 70* C.,contacting said treated fiber or film with water or an alkali solutionso as to generate sufficient thermal energy to fix the dye into theinternal structure of the fiber or film, washing and drying said fiberor film.